Dyes and dye-donor elements for use in thermal dye transfer

ABSTRACT

Dye donor element for use according to thermal dye sublimation transfer comprising a support having thereon a dye layer comprising at least one heterocyclic hydrazono dye, wherein said dye corresponds to the general formula: 
     
         A=N-N=Het 
    
     wherein A is a carbocyclic or heterocyclic coupler group or a cyclic reactive methylene system, which may carry at least one substituent, and Het is a heterocyclic nucleus, which may carry at least one substituent.

CROSS-REFERENCE TO RELATED U.S. APPLICATIONS

This application is a divisional of application Ser. No. 08/169,335,filed on Dec. 17, 1993, now U.S. Pat. No. 5,468,258.

FIELD OF THE INVENTION

The present invention relates to novel magenta and cyan heterocyclichydrazono dyes (also called azino dyes), to dye-donor elements andblack-coloured dye-donor elements comprising such dyes for use accordingto thermal dye transfer methods.

BACKGROUND OF THE INVENTION

Thermal dye sublimation transfer also called thermal dye diffusiontransfer is a recording method in which a dye-donor element providedwith a dye layer containing sublimable dyes having heat transferabilityis brought into contact with a receiver sheet and selectively, inaccordance with a pattern information signal, is heated by means of athermal printing head provided with a plurality of juxtaposedheat-generating resistors, so that dye is transferred from theselectively heated regions of the dye-donor element to the receiversheet and forms a pattern thereon, the shape and density of which is inaccordance with the pattern and intensity of heat applied to thedye-donor element.

A dye-donor element for use according to thermal dye sublimationtransfer usually comprises a very thin support e.g. a polyester support,one side of which has been covered with a dye layer comprising theprinting dyes. Usually, an adhesive or subbing layer is provided betweenthe support and the dye layer. Normally, the opposite side of thesupport is covered with a slipping layer that provides a lubricatedsurface against which the thermal printing head can pass withoutsuffering abrasion. An adhesive layer may be provided between thesupport and the slipping layer.

A dye-image receiving element for use according to thermal dyesublimation transfer usually comprises a support, e.g. paper or atransparant film coated with a dye-image receiving layer, into which thedye can diffuse more readily. An adhesive layer may be provided betweenthe support and the receiving layer. A releasing agent may be containedin the receiving layer or in a separate layer on top of said receivinglayer to improve the releasability of the receiving element from thedonor element after the dye transfer has been effected.

The dye layer can be a monochromic dye layer or it may comprisesequential repeating areas of differently coloured dyes e.g. dyes havinga cyan, magenta, yellow, and optionally black-colour hue. When adye-donor element containing three or more primary colour dye areas isused, a multicolour image can be obtained by sequentially performing thedye transfer process steps for each colour area.

Black-coloured images can be obtained by thermal dye sublimationtransfer printing either by sequentially performing the dye transferprocess steps for the three primary colours cyan, magenta, and yellow bymeans of a dye-donor element comprising sequential repeating areas ofcyan, magenta, and yellow coloured dyes or by performing only onetransfer step by means of a dye-donor element having a black-coloureddye layer containing a fixture of yellow, magenta, and cyan colouredimage dyes. The latter of these two methods is preferred because of i.a.the ease of manufacturing the donor element containing only one dyearea, less time-consuming recording with only one transfer step, andavoiding the problem of transfer in register of the respective dyes inthe respective dye areas. Mixtures of yellow, magenta, and cyan dyes forforming a black-coloured dye layer of such a black-coloured dye-donorelement have been described in e.g. European patent application N°92202157.1, EP 453,020, U.S. Pat. No. 4,816,435, and JP 01/136,787.

An important application of the recording of monochromic black images bythermal dye sublimation transfer is the recording on transparant filmreceiver of hard copies of medical diagnostic images formed by e.g.ultrasound techniques. Such a hard copy is considered to be anecologically more acceptable and more convenient substitute for theblack-and-white silver hard copy formed by development of conventionalphotographic silver halide film materials where processing solutionscomprising silver salt residues have to be treated carefully beforedisposal.

In order to be a really valid substitute for conventional photographicsilver halide materials the black-coloured mixture of organic dyes usedin thermal dye sublimation transfer printing should behave optically asblack silver.

In the medical world physicians and radiologists evaluate X-rayphotographs or other images on a light box or negatoscope. These lightboxes contain fluorescent lamps as light source. The spectral emissionof fluorescent lamps depends on the phosphors used in the fluorescentlamp, said phosphors having peak emissions. As a result, fluorescentlamps do not show a continuous emission spectrum. Furthermore, there isno standardization in the type of fluorescent lamp used in saidnegatoscopes.

There is not so much a problem when viewing classical medical imagescomposed of silver metal on the light boxes, since the spectralabsorption characteristics of silver are constant over the whole visiblespectrum. The hue of the silver image does not change whatever thespectral properties of the light source are, by which the image is beingviewed.

However, when the black image is composed of coloured dyes, problems ofhue changes may arise, because the spectral absorption characteristicsof organic dyes are not constant over the whole range of the visiblespectrum. A black-coloured dye mixture having a neutral look when viewedwith one light source will not have a neutral look when viewed with aspectrally different light source. This phenomenon of hue change of animage when viewed with a different light source is highly unwanted,especially when medical diagnostic images have to be evaluated.

The characteristics of colour dyes that can be used for composingblack-coloured dye mixtures have been further described in EP-A 453020.

Many of the dyes proposed so far for use in thermal dye sublimationtransfer are not sufficient in performance since they yield inadequatetransfer densities at reasonable coating coverages, or because they haveinadequate spectral characteristics for substractive colour systems, orbecause they have a poor light-fastness.

As mentioned before, for forming a black record by thermal dyesublimation transfer the transfer currently has been performed by meansof a dye-donor element having a black-coloured layer containing amixture of yellow, magenta, and cyan coloured dyes.

However, the conventional materials are insufficient in performance inthat the density of the transferred black image obtained therefrom istoo low, especially When transfer has been performed onto a transparentdye-image receiving element.

To fulfil the above described requirements for black-coloured dyemixtures, it would be an advantage that the colour dyes have a highmolar extinction coefficient at the absorption maximum combined withhigh side absorptions. As a consequence, fewer dyes and/or smalleramounts of dyes would be needed to reach higher black density values,which would also result in less overloading of the polymer matrix of thedye donor layer.

3. Summary of the invention.

It is therefore an object of the present invention to provide novelmagenta and cyan heterocyclic hydrazono dyes having a high molarextincton coefficient.

It is another object of the present invention to provide novel magentaand cyan heterocyclic hydrazono dyes having a high molar extinctioncoefficient combined with high side absorptions.

It is another object of the present invention to provide dye donorelements, in particular magenta or cyan dye donor elements, that yieldtransferred dye images having high densities.

It is a further object of the present invention to provide black dyedonor elements that yield transferred black images having highdensities.

Further objects will become apparent from the description hereinafter.

In accordance with the present invention a dye donor element for useaccording to thermal dye sublimation transfer is provided, said dyedonor element comprising a support having thereon a dye layer comprisingat least one heterocyclic hydrazono dye, wherein said at least oneheterocyclic hydrazono dye corresponds to the following general formula(I): ##STR1## wherein: Z represents the atoms necessary to complete aheterocyclic ring system, a substituted heterocyclic ring systemincluding a heterocyclic ring system carrying a fused-on aliphatic oraromatic ring system,

Q₁, and Q₂ (same or different) represents hydrogen or a substituent e.g.an alicyclic, aromatic, or heterocyclic ring system including such ringsystem in substituted form,

R² represents an alkyl group, a substituted alkyl group, a cycloalkylgroup, a substituted cycloalkyl group, an aryl group, or substitutedaryl group,

m is 0 or 1 and

Y represents the atoms necessary to complete a heterocyclic couplersystem or substituted heterocyclic coupler system.

The present invention also provides novel dyes corresponding to generalformula I.

The present invention further provides a dyed receiving elementcomprising a dye in image-wise distribution, formed by thermal dyesublimation transfer using a dye-donor element according to the presentinvention.

The present invention also provides a method of forming an image byimage-wise heating a dye-donor element comprising a support havingthereon a dye layer comprising a binder and at least one dyecorresponding to any of the above general formula I, and causingtransfer of the image-wise heated dye to a receiver sheet.

4. Detailed description of the invention.

The dyes of the invention corresponding to the general formula (I) canbe prepared according to methods known to those skilled in the art oforganic synthesis, e.g. by oxidative coupling of appropriateheterocyclic hydrazones, preferably heterocyclic sulfonylhydrazones,with the appropriate couplers in a basic environment. This will becomemore apparent from the preparation examples hereinafter.

Appropriate couplers have been described in EP 279,467, EP 480,252, EP454,049, EP 362,808, JA 3016792, JA 02084391, JA 03081192, and JA02181747.

The synthesis of hydrazono and sulfonylhydrazono compounds has beendescribed in FR 1,444,971, GB 1,301,657, GB 1,286,831, U.S. Pat. Nos.3,622,327, 3,839,035, GB 1,392,433, and U.S. Pat. No. 4,004,926.

Representatives of dyes that can be used according to the presentinvention are listed in the following Table 1. ##STR2## The followingpreparation example 1 illustrates the synthesis of the dyescorresponding to the general formula (I).

Preparation example: synthesis of dye C10

Dye C1 is prepared according to the following reaction scheme 1.Compounds E and F are prepared according to methods known to thoseskilled in the art of organic synthesis. ##STR3## 8 g (14.8 mmole) ofcompound E, 3.3 g (16.3 mmole) of compound F, and 3.3 ml of ammoniumhydroxide (3 equivalents) are dissolved in 200 ml of ethanol. Thesolution is refluxed. A solution of 10.3 g of potassium cyanoferrate(III) in 50 ml of water is added dropwise thereto and the resultingsolution is stirred for 10 min. After cooling the precipitate isfiltered and purified by boiling in 100 ml of tert-butyl methyl ether.

Yield: 3.2 g of dye C1.

The dyes can be used as filter dyes e.g. for silver halide colourphotographic materials and also as antihalation dyes. They can be usedin inkjet printing, resistive ribbon printing, in inks e.g. for laserapplications, in textile, in lacquers, and in paints. They can also beused for transfer printing on fabrics.

According to a preferred embodiment of the present invention the dyesare used in the dye layer of a dye-donor element for thermal dyesublimation transfer.

The dye layer of the dye-donor element is formed preferably by addingthe dyes, a polymeric binder medium, and other optional components to asuitable solvent or solvent mixture, dissolving or dispersing byball-milling these ingredients to form a coating composition that isapplied to a support, which may have been provided first with anadhesive or subbing layer, and dried.

The dye layer thus formed has a thickness of about 0.2 to 5.0 μm,preferably 0.4 to 2.0 μm, and the amount ratio of dye to binder rangesfrom 9:1 to 1:3 by weight, preferably from 2:1 to 1:2 by weight.

The following polymers can be used as polymeric binder: cellulosederivatives, such as ethyl cellulose, hydroxyethyl cellulose,ethylhydroxy cellulose, ethylhydroxyethyl cellulose, hydroxypropylcellulose, methyl cellulose, cellulose nitrate, cellulose acetateformate, cellulose acetate hydrogen phthalate, cellulose acetate,cellulose acetate propionate, cellulose acetate butyrate, celluloseacetate pentanoate, cellulose acetate benzoate, cellulose triacetate;vinyl-type resins and derivatives, such as polyvinyl alcohol, polyvinylacetate, polyvinyl butyral, copolyvinyl butyral-vinyl acetal-vinylalcohol, polyvinyl pyrrolidone, polyvinyl acetoacetal, polyacrylamide;polymers and copolymers derived from acrylates and acrylate derivatives,such as polyacrylic acid, polymethyl methacrylate and styrene-acrylatecopolymers; polyester resins; polycarbonates;poly(styrene-co-acrylonitrile); polysulfones; polyphenylene oxide;organosilicones such as poly-siloxanes; epoxy resins and natural resins,such as gum arabic. Preferably, the binder for the dye layer of thepresent invention comprises cellulose acetate butyrate orpoly(styrene-co-acrylonitrile).

The dye-donor element of the present invention can be used for therecording of a coloured image together with primary colour dye-donorelements comprising respectively a magenta dye or a mixture of magentadyes, a cyan dye or a mixture of cyan dyes and a yellow dye or a mixtureof yellow dyes.

Any dye can be used in such a primary colour dye layer provided it iseasily transferable to the dye-image-receiving layer of the receiversheet by the action of heat.

The dyes of the present invention can be used alone or mixed with oneanother, or even mixed with other primary colour dyes.

The dyes according to formula (I) are particularly useful for makingblack and white images using the thermal transfer process. Such blackand white images may be composed of 3 primary dyes, i.e. yellow, magentaand cyan, that are transferred in sequence to an image receiving elementor said black and white images may be obtained by transferring a blackmixture of several dyes. In each case at least one of the constitutingdyes will be a dye according to formule (I).

Typical and specific examples of other primary colour dyes for use inthermal dye sublimation transfer have been described in e.g. EP 400,706,EP 209,990, EP 216,483, EP 218,397, EP 227,095, EP 227,096, EP 229,374,EP 235,939, EP 247,737, EP 257,577, EP 257,580, EP 258,856, EP 279,330,EP 279,467, EP 285,665, U.S. Pat. Nos. 4,743,582, 4,753,922, 4,753,923,4,757,046, 4,769,360, 4,771,035, JP 84/78,894, JP 84/78,895, JP84/78,896, JP 84/227,490, JP 84/227,948, JP 85/27,594, JP 85/30,391, JP85/229,787, JP 85/229,789, JP 85/229,790, JP 85/229,791, JP 85/229,792,JP 85/229,793, JP 85/229,795, JP 86/268,493, JP 86/268,494, JP85/268,495, and JP 86/284,489.

The coating layer may also contain other additives, such as curingagents, preservatives, organic or inorganic fine particles, dispersingagents, antistatic agents, defoaming agents, viscosity-controllingagents, these and other ingredients having been described more fully inEP 133,011, EP 133,012, EP 111,004, and EP 279,467.

Any material can be used as the support for the dye-donor elementprovided it is dimensionally stable and capable of withstanding thetemperatures involved, up to 400° C. over a period of up to 20 msec, andis yet thin enough to transmit heat applied on one side through to thedye on the other side to effect transfer to the receiver sheet withinsuch short periods, typically from 1 to 10 msec. Such materials includepolyesters such as polyethylene terephthalate, polyamides,polyacrylates, polycarbonates, cellulose esters, fluorinated polymers,polyethers, polyacetals, polyolefins, polyimides, glassine paper andcondenser paper. Preference is given to a support comprisingpolyethylene terephthalate. In general, the support has a thickness of 2to 30 μm. The support may also be coated with an adhesive of subbinglayer, if desired.

The dye layer of the dye-donor element can be coated on the support orprinted thereon by a printing technique such as a gravure process.

A dye-barrier layer comprising a hydrophilic polymer may also beemployed between the support and the dye layer of the dye-donor elementto enhance the dye transfer densities by preventing wrong-way transferof dye backwards to the support. The dye barrier layer may contain anyhydrophilic material that is useful for the intended purpose. Ingeneral, good results have been obtained with gelatin, polyacrylamide,polyisopropyl acrylamide, butyl methacrylate-grafted gelatin, ethylmethacrylate-grafted gelatin, ethyl acrylate-grafted gelatin, cellulosemonoacetate, methylcellulose, polyvinyl alcohol, polyethyleneimine,polyacrylic acid, a mixture of polyvinyl alcohol and polyvinyl acetate,a mixture of polyvinyl alcohol and polyacrylic acid, or a mixture ofcellulose monoacetate and polyacrylic acid. Suitable dye barrier layershave been described in e.g. EP 227,091 and EP 228,065. Certainhydrophilic polymers e.g. those described in EP 227,091 also have anadequate adhesion to the support and the dye layer, so that the need fora separate adhesive or subbing layer is avoided. These particularhydrophilic polymers used in a single layer in the dye-donor elementthus perform a dual function, hence are referred to asdye-barrier/subbing layers.

Preferably the reverse side of the dye-donor element has been coatedwith a slipping layer to prevent the printing head from sticking to thedye-donor element. Such a slipping layer would comprise a lubricatingmaterial such as a surface-active agent, a liquid lubricant, a solidlubricant or mixtures thereof, with or without a polymeric binder. Thesurface-active agents may be any agents known in the art such ascarboxylates, sulfonates, phosphates, aliphatic amine salts, aliphaticquaternary ammonium salts, polyoxyethylene alkyl ethers, polyethyleneglycol fatty acid esters, fluoroalkyl C₂ -C₂₀ aliphatic acids. Examplesof liquid lubricants include silicone oils, synthetic oils, saturatedhydrocarbons, and glycols. Examples of solid lubricants include varioushigher alcohols such as stearyl alcohol, fatty acids and fatty acidexters. Suitable slipping layers have been described in e.g. EP 138,483,EP 227,090, U.S. Pat. Nos. 4,567,113, 4,572,860, 4,717,711. Preferablythe slipping layer comprises a styrene-acrylonitrile copolymer or astyrene-acrylonitrile-butadiene copolymer or a mixture thereof or apolycarbonate as described in European patent application no.91202071.6, as binder and a polysiloxane-polyether copolymer orpolytetrafluoroethylene or a mixture thereof as lubicrant in an amountof 0.1 to 10% by weight of the binder or binder mixture.

The support for the receiver sheet that is used with the dye-donorelement may be a transparent film of e.g. polyethylene terephthalate, apolyether sulfone, a polyimide, a cellulose ester or a polyvinylalcohol-co-acetal. The support may also be a reflective one such as abaryta-coated paper, polyethylene-coated paper or white polyester i.e.white-pigmented polyester. Blue-coloured polyethylene terephthalate filmcan also be used as support.

To avoid poor adsorption of the transferred dye to the support of thereceiver sheet this support must be coated with a special layer calleddye-image-receiving layer, into which the dye can diffuse more readily.The dye-image-receiving layer may comprise e.g. a polycarbonate, apolyurethane, a polyester, a polyamide, polyvinyl chloride,polystyrene-co-arcylonitrile, polycaprolactone, or mixtures thereof. Thedye-image receiving layer may also comprise a heat-cured product ofpoly(vinyl chloride/co-vinyl acetate/co-vinyl alcohol) andpolyisocyanate. Suitable dye-image-receiving layers have been describedin e.g. EP 133,011, EP 133,012, EP 144,247, EP 227,094, and EP 228,066.

In order to improve the light-fastness and other stabilities of recordedimages UV-absorbers, singlet oxygen quenchers such as HALS-compounds(Hindered Amine Light Stabilizers) and/or antioxidants can beincorporated into the dye-image-receiving layer.

The dye layer of the dye-donor element or the dye-image-receiving layerof the receiver sheet may also contain a releasing agent that aids inseparating the dye-donor element from the receiver sheet after transfer.The releasing agents can also be incorporated in a separate layer on atleast part of the dye layer and/or of the dye-image-receiving layer.Suitable releasing agents are solid waxes, fluorine- orphosphate-containing surface-active agents and silicone oils. Suitablereleasing agents have been described in e.g. EP 133,012, JP 85/19,138,and EP 227,092.

The dye-donor elements according to the invention are used to form a dyetransfer image, which process comprises placing the dye layer of thedye-donor element in face-to-face relation with the dye-image-receivinglayer of the receiver sheet and image-wise heating from the back of thedye-donor element. The transfer of the dye is accomplished by heatingfor about several milliseconds at a temperature of 400° C.

When the process is performed for but one single colour, a monochromicdye transfer image is obtained. A multicolour image can be obtained byusing a dye-donor element containing three or more primary colour dyesand sequentially performing the process steps described above for eachcolour. The above sandwich of dye-donor element and receiver sheet isformed on three occasions during the time when heat is applied by thethermal printing head. After the first dye has been transferred, theelements are peeled apart. A second dye-donor element (or another areaof the dye-donor element with a different dye area) is then brought inregister with the dye-receiving element and the process is repeated. Thethird colour and optionally further colours are obtained in the samemanner.

In addition to thermal heads, laser light, infrared flash, or heatedpens can be used as the heat source for supplying heat energy. Thermalprinting heads that can be used to transfer dye from the dye-donorelements of the present invention to a receiver sheet are commerciallyavailable. In case laser light is used, the dye layer or another layerof the dye element has to contain a compound that absorbs the lightemitted by the laser and converts it into heat e.g. carbon black.

Alternatively, the support of the dye-donor element may be anelectrically resistive ribbon consisting of e.g. a multilayer structureof a carbon-loaded polycarbonate coated with a thin aluminium film.Current is injected into the resistive ribbon by electrically addressinga printing head electrode resulting in highly localized heating of theribbon beneath the relevant electrode. The fact that in this case theheat is generated directly in the resistive ribbon and that it is thusthe ribbon that gets hot leads to an inherent advantage in printingspeed using the resistive ribbon/electrode head technology as comparedto the thermal head technology, according to which the various elementsof the thermal head get hot and must cool down before the head can moveto the next printing position.

The following examples illustrate the invention in more detail without,however, limiting the scope thereof.

EXAMPLE 1

The absorption maxima (λmax) of the dyes identified below weredetermined. The results are listed in Table 2.

                  Table2                                                          ______________________________________                                               Dye   λ.sub.max (nm)                                            ______________________________________                                               C1 (a)                                                                              615                                                                     C2 (b)                                                                              565                                                                     C3 (c)                                                                              565                                                              ______________________________________                                         (a) determined in dichloromethane/methanol (2:8)                              (b) determined in dichloromethane/methanol (1:1)                              (b) determined in dichloromethane/methanol/dimethylformamide (1:8:1)     

EXAMPLE 2

Receiver sheets were prepared by coating a subbed polyethyleneterephthalate film having a thickness of 175 μm with adye-image-receiving layer from a solution in ethyl methyl ketone of 3.6g/m² of poly(vinyl chloride/co-vinyl acetate/co-vinyl alcohol) (VinyliteVAGD supplied by Union Carbide), 0.336 g/m² of diisocyanate (DesmodurN3300 supplied by Bayer AG), and 0.2 g/m² of hydroxy-modifiedpolydimethylsiloxane (Tegomer H SI 2111 supplied by Goldschmidt).

Dye-donor elements for use according to thermal dye sublimation transferwere prepared as follows.

A solution in methyl ethyl ketone of 0.5 % by weight of dye C1 and 0,5 %by weight of poly(styrene-co-acrylonitrile) (PSA) (Luran 388S, suppliedby BASF Germany) was prepared.

A dye layer having a wet thickness of 100 μm was coated from thissolution on a polyethylene terephthalate film support having a thicknessof 6 μm and carrying a conventional subbing layer. The resulting dyelayer was dried by evaporation of the solvent.

The opposite side of the film support was coated with a subbing layer ofa copolyester comprising ethylene glycol, adipic acid, neopentyl glycol,terephthalic acid, isophthalic acid, and glycerol.

The resulting subbing layer was covered with a solution in methyl ethylketone of 0.5 g/m² of a polycarbonate having the following structuralformula to form a-heat-resistant layer: ##STR4## wherein x=55 mol % andy=45 mol %.

Finally, a top layer of polyether-modified polydimethylsiloxane(Tegoglide 410, Goldschmidt) was coated from a solution in isopropanolon the resulting heat-resistant polycarbonate layer.

The dye-donor element was printed in combination with a receiver sheetin a Mitsubishi colour video printer CP100E.

The receiver sheet was separated from the dye-donor element and thecolour density value of the recorded image was measured in reflex bymeans of a Macbeth TR 924 densitometer in the red, green, and blueregions in Status A mode.

The obtained values were as follows:

D_(max) =60; behind red filter 60, green filter 28 and blue filter 9. Itcan thus be seen that dye C1 exhibits a rather broad spectrum whichmakes the dye suitable for making black and white images.

We claim:
 1. A dye donor element comprising a support having on one sidethereon a dye layer comprising at least one unreacted heterocyclichydrazono dye compound, and having on the other side thereon a slippinglayer, wherein said at least one heterocyclic hydrazono dye correspondsto the following general formula (I): ##STR5## wherein: Z represents theatoms necessary to complete a heterocyclic ring system, or a substitutedheterocyclic ring system, including a heterocyclic ring system carryinga fused-on aliphatic or aromatic ring system,Y represents the atomsnecessary to complete a heterocyclic coupler system or substitutedheterocyclic coupler system, R² represents an alkyl group, a substitutedalkyl group, a cycloalkyl group, a substituted cycloalkyl group, an arylgroup, or a substituted aryl group, m is 0 or 1, and each of Q₁ and Q₂independently represents hydrogen or a substituent.
 2. A dye donorelement according to claim 1, wherein the dye layer contains a binderselected from the group consisting of cellulose acetate butyrate andpoly(styrene-co-acrylonitrile).
 3. A dye donor element according toclaim 1, wherein said heterocyclic hydrazono dye together with other dyeconstitutes a black mixture.